The objective of this grant is to develop the applicant's skills in neurogenetic research methodology and to apply this knowledge to independent research investigating the association between genes and their expression on hemispherically specialized information processing (i.e., lateralized information processing- LIP) among children with ADHD. The candidate's graduate work researched lateralized information processing in an adult ADHD population and identified atypical cerebral asymmetries (ACA) that were modulated by attentional states and restricted to early stages of processing. Currently, the applicant is evaluating ACA as a quantitative risk-factor for ADHD. Behavioral and EEG measures of LIP are being collected on 300 families with two affected ADHD siblings with the primary goal of identifying LIP endophenotypes by evidence of familiarity and association with neurocognitive variants underlying behavioral constructs in ADHD (see Preliminary Studies). Data collection and publications from this study will be completed while the candidate is in the mentorship phase of the proposed study period. The mentorship period will be used to develop the candidate's expertise in neurogenesis and neurogenetic methodologies, including gene influences on neurogenesis of cerebral lateralization, methods of behavior genetic research, and the use of bioinformatics tools for neurogenetic research. This training will directly support the applicant's independent research project that will investigate the genetics of LIP and its association with ADHD via data collection of a control sample matched to the previously collected ADHD sample of children and adolescents in order to: 1) analyze the strength of association of lateralized brain function (behavioral, EEG, fMRI) with ADHD status, 2) analyze the relationship of cognitive deficits with ACA in ADHD and non- ADHD samples;and 3) identify genes involved in the neurogenesis of ACA using traditional gene detection methods (quantitative transmission disequilibrium testing-QTDT) and gene expression arrays. This work researches fundamental quantitative mechanisms in ADHD by utilizing psychophysics and laterally techniques to investigate hemisphere specific information processing that may underlie cognitive and behavior sequelae in this condition.